Rotating Laser Welding for Stable Coil End Joints
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Solution Overview
Problem
Current laser welding methods for stator coils in hybrid and electric vehicles are inefficient, leading to prolonged processing times and potential spattering issues due to uneven energy distribution and molten pool expansion.
Innovation Solution
A welding method and laser device that uses rotational irradiation of laser light with a spot diameter equal to or larger than the rotating diameter, ensuring central energy supply and preventing excessive heat concentration, thereby stabilizing the molten pool and reducing spattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser light is concentrated on a small spot for welding, then welding precision is improved, but heat concentration causes spattering and molten pool expansion
Solution Approach 1:
The patent applies dynamic motion to the laser beam by rotating it around the welding point at a specific speed. This dynamic irradiation prevents heat concentration at a single spot, eliminating spattering while maintaining welding precision. The laser beam moves in a circular path with a diameter larger than the spot diameter, creating a balanced thermal distribution.
Solution Approach 2:
The patent changes the irradiation parameters by specifying that the rotation diameter of the laser beam is larger than the spot diameter. This parameter adjustment transforms the heat distribution pattern from concentrated to distributed, preventing molten pool expansion while maintaining effective welding energy input.
2Productivity
If laser welding is performed on small welding surfaces, then productivity is improved through compact design, but processing time increases due to limited energy distribution
Solution Approach 1:
The rotating laser beam dynamically distributes energy across the welding surface, enabling faster heating and melting on small surfaces. The rotation creates a sweeping effect that rapidly distributes thermal energy, reducing processing time while maintaining the compact welding setup.
Solution Approach 2:
The periodic rotation of the laser beam creates rhythmic heating cycles that efficiently melt the welding surface. This periodic energy input optimizes the melting process on small surfaces, reducing the total time required compared to static irradiation.
3Loss of time
If high energy density is applied to melt the welding surface quickly, then processing time is reduced, but excessive heat causes spattering and poor welding quality
Solution Approach 1:
The dynamic rotation of the laser beam distributes high energy density across multiple locations over time, achieving rapid melting without concentrating excessive heat at one spot. This prevents spattering while maintaining fast processing speed through efficient energy utilization.
Solution Approach 2:
The patent changes the energy distribution parameter by using a rotation diameter larger than the spot diameter, which transforms the energy application from concentrated to distributed. This allows high total energy input for fast processing while maintaining low local energy density to prevent spattering.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for faster melting and formation of a clean molten ball, enhancing welding quality and reducing processing time while maintaining high productivity.
Implementation Method 1
the welding surface starts melting from the central portion and gradually melts toward the end portion due to thermal conduction
Implementation Method 2
the central portion of the welding surface is normally irradiated with the laser light. Therefore, it is possible to supply sufficient energy to the central portion of the welding surface, and the welding surface starts melting from the central portion
Data Source
AI summary
A welding method includes: arranging end portions of a first member and a second member next to each other facing an end surface of the end portions towards a laser device; performing rotational irradiation to the end surface of the end portions of the first member and the second member with laser light at a predetermined rotating diameter, wherein a spot diameter of the laser light is set to be equal to or larger than the rotating diameter, and wherein an irradiation region of the laser light by the rotational irradiation is set to extend over the first member and the second member.